Causing red dots on the legs, very itchy may be insect bite dermatitis, eczema and so on. 1. Insect bite dermatitis: the bite of mites, mosquitoes, midges, bedbugs and other arthropods can lead to localized allergic and inflammatory reactions, resulting in red dots, accompanied by itching symptoms. 2. Eczema: related to a variety of internal and external factors, such as allergies, infections, local irritation, environmental changes, endocrine changes and so on. It can lead to the appearance of papules, erythema, scales and other polymorphic skin lesions on the legs, accompanied by significant itching. If the red spots on the legs are itchy, you should go to the regular hospital in time to identify the cause of the disease and choose the appropriate method of treatment under the guidance of a professional doctor.